Crystal holder



J. G. BEARD CRYSTAL HOLDER Dec. 3, 1935.

Filed Oct. 18, 1934 INVENTOR Josep/z GTBeard.

ATTORNEY Car Patented Dec. 3, 1935 UNITED STATES CRYSTAL HOLDER JosephG. Beard, Springfield, Mass., assignor to Westinghouse Electric &Manufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania Application October 18, 1934, Serial No. 748,853

6 Claims.

My invention relates to crystal holders and more particularly toimprovements in such holders for the protection of the crystals housedtherein, to prevent wear and possible breakage thereof during handling.

In connection with the stabilization of the frequency of radioapparatus, it has been standard practice to utilize some mechanicalvibrating element for the purpose, having a natural frequency ofvibration of the order of that desired in the radio circuit. One of thebest known elements of this character is the quartz crystal. Suchcrystals are prepared from natural quartz crystals and are reasonablysmall in size, the size or more particularly the thickness thereofdecreasing as the desired frequency increases in value so that at thehigher radio frequencies, crystals become very thin and fragile.

The crystals, when once cut and calibrated,

are mounted in their holders and the holders are then usually sealed toprevent unauthorized tampering with the crystal. In mounting crystals inthe holders, the crystals are loosely placed within a spacing elementlocated within the holder and electrodes are positioned one below andone above the crystal, the crystal usually resting upon the lowerelectrode. The upper electrode sometimes rests upon the upper surface ofthe crystal and in direct contact therewith, and in other instances, theupper electrode is maintained in spaced relationship to the crystal.

In either case, however, it has been found that the looseness of thecrystal in the holder permits it to move about in the holder and becomesubject to shocks and jars, to which the holder may be exposed. Thisoccurs during shipment of the crystal holder and its contents, and alsowhen the holder is embodied in apparatus such as portable frequencystandards for checking the frequency of broadcast stations, thesestandards being mounted on trucks whereby they may conveniently be movedto any desired location. These jars and shocks are very apt to crack thecrystal and render it useless or cause wearing of the crystal resultingin a change from its calibrated frequency, requiring in either case thata new crystal be prepared and substituted therefor.

Consequently, it is an object of my invention to eliminate such hazardsin the handling of crystal holders and their contents.

A further object of my invention is to provide a holder with means forprotecting the crystal against shocks or jars when such crystal is notin use.

A further object of my invention is to provide a crystal holder withmeans which will protect a crystal against injury during handling andwhich will automatically permit the crystal to function upon connectingthe holder into the apparatus with which it is to be used.

Additional objects of my invention will be disclosed in detail in thefollowing description thereof, taken in connection With the accompanying.drawing, wherein I have disclosed two embodiments of my invention.

Figs. 1, 2 and 3 relate to one embodiment wherein the upper electroderests on the upper surface of the crystal and in direct contacttherewith; and,

Fig. 4 illustrates the second embodiment of my invention wherein theupper electrode is maintained in spaced relationship to the crystal.

Referring to Figs. 1, 2 and 3, the crystal holder disclosed is comprisedof two parts, a. base or crystal supporting portion I and the cover 3for enclosing the crystal 5. The base portion is preferably of metal andwhen of such material, it comprises the lower electrode. The crystal issupported on this electrode and maintained against substantial lateralmovement or shifting by means of a plurality of upstanding pins 1 ofinsulating material, so arranged as to permit of the crystal beingdisposed between them to prevent lateral shifting thereof. The upperelectrode 9 rests on the upper surface of the crystal and in directcontact therewith.

A suitable bar II preferably of metal, extends across the upper surfaceof the upper electrode and is made integral therewith or is otherwisesuitably attached thereto, the bar being of such a length as to extend asubstantial distance on either side of the electrode.

The cover of the holder rests on the base portion and is suitablyattached thereto by any well known mechanical means, such as bolts ormachine screws and encloses the crystal, the upper electrode and the barextending thereacross. The center of the cover is perforated andthreaded to receive a terminal I3 which is electrically connected to theupper electrode and cross bar by means of a very weak and flexiblespring l5 joining the terminal and the cross bar at its center, thespring exerting no appreciable pressure against the upper electrode, butfunctioning merely as a flexible connecting link.

On the upper surface of the cover, there is mounted a leaf spring llpreferably of a shape to conform to the shape of the holder, and this isattached to the cover at one spot I9 leaving the spring substantiallyfree except at its point of attachment. At diametrically opposite pointson the cover directly above the ends of the bar element, openings areprovided through which extend pins 2|, these pins being preferably ofinsulating material, and attached to the leaf spring. The pins are ofsuch length as to transmit pressure from the spring against the ends ofthe bar element. Pressure on the ends of the bar element will naturallybring pressure to bear against the crystal and between the crystal andits electrodes, thus preventing movement of the crystal should theholder be subject to jars or shocks. Consequently, the crystal underpressure will be protected against these hazards.

That portion of the circular spring diametrically opposite to the pointof attachment to the cover may be bent upwardly to form a lip 23 toconveniently receive and permit of the insertion of a finger 25 or othersuitable element. This element may constitute a part of the apparatus,in connection with which the crystal is to be used, and may be sodisposed as, to automatically raise the spring I! upon positioning theholder in said apparatus. Thus as the finger finds its way under thespring it lifts it from its normal position, thereby removing thepressure on the cross bar and consequently removing the pressure fromthe crystal. The crystal thereby becomes free to vibrate and is adaptedto function in the control of the frequency of the apparatus.

The radio apparatus may be so constructed that upon inserting the holderin its proper position in the apparatus, the bottom electrode and theupper terminal will both make suitable contacts with the apparatus,whereby the crystal will be operatively included in the circuit. At thesame time, the spring may be lifted by the finger cr other suitableelement on the apparatus, plac ing the crystal in condition foroperation.

In the construction of Fig. 4, the holder comprises a base 29 preferablyof metal constituting the bottom electrode, this electrode beingprovided with a shoulder, on which is mounted a cylindrical tube 3| ofinsulating material, such as quartz, to constitute the cylindrical wallsof the holder. The upper electrode 33 is provided with a similarcircumferential shoulder as that of the bottom electrode, and is mountedon the upper edge of the cylindrical walls. The crystal 35 is positionedto rest on the bottom electrode and in direct contact therewith, beingsuitably spaced from the walls of the housing by a crystal, spacingelement 31. The walls of the holder are of such a height as to providethe necessary spacing between the crystal and the upper electrode.

In the center of the bottom electrode there is an opening extendingclear through, to the elec-.

'trode, in which opening a pin 39 of insulating material is disposed,whichisattached at its external end to a leaf spring 4|, one end of,which, is secured to the bottom electrode, the other end of which isdeformed to form a lip 43 to permit of, easy and convenientinsertion ofan element45 adapted to separate the spring from the bottom electrode.In its separated position, the crystal is permitted to rest in contactwith the bottom electrode and is adapted to function as a frequencycontrolling device. Upon withdrawal of the separating element, however,the spring member will drive the pin upwardly against the crystal and isof sufficient length to clamp the crystal to the upper electrode againstmovement with respect thereto,

The element for separating the spring from the bottom electrode topermitof the oscillation of the crystal may comprise part of the radioapparatus, in which the crystal is to be used, and will automaticallyrender the crystal operative upon the connection of the holder into theapparatus. As in connection with the embodiment of Figs. 1, 2 and 3,contact with the electrodes and separation of the spring from the bottomelectrode to permit of the operation of the crystal may take placesimultaneously when connecting the holder into the apparatus with whichit is to be used.

Since the spring separating element of the embodiment of Fig. 4 becomesclamped against 1 the bottom electrode and in surface contact therewith,it may constitute at the same time one of the connections which connectsthe crystal into the circuit.

While I have disclosed my invention in great 1 detail, it is subject tominor changes without departing from the scope or my invention, and I,therefore, do not desire to be limited to the de-. tails, as shown,except as may be determined by the prior art and the appended claims.

I claim as my invention:

l. A crystal holder comprising in combination a support for a crystalcomprising an electrode, a second electrode in Spaced relationship tosaid first electrode, a crystal between said electrodes, spring meansexternal of said holder for normally maintaining said crystal inpressure engagement with one of said electrodes, said means beingreleasable whereby to remove the pressure from said crystal to permit ofvibrational movement thereof.

2. A crystal holder comprising in combination a support for a crystalcomprising an electrode and a crystal on said electrode, a cover forsaid holder, a spring affixed to said cover externally thereof, andmeans extending through said cover to transmit the pressure of saidspring to said electrode and crystal.

3. A crystal holder comprising in combination a support for a crystalcomprising an electrode and a crystal on said electrode, a cover forsaid holder, a spring affixed to said cover externally thereof, andmeans extending through said cover to transmit the pressure of saidspring to said electrode and crystal, and means for releasing saidcrystal and electrode from the pressure exerted by said spring.

4. In combination, radio apparatus whose frequency is to be controlled,a crystal control unit for controlling the frequency of said apparatus,said control unit comprising a holder for a crystal, means on saidholder for normally maintaining said crystal under pressure againstvibration or accidental movement, and means on said apparatus forremoving said pressure means from engagement with said crystal duringoperation of said crystal in said apparatus.

5. A crystal housing comprising means for supporting a crystal,resilient means external of said housing for bringing pressure to bearagainst a crystal in said housing and means for releasing such crystalfrom the pressure influence of said resilient means.

6. A crystal housing comprising an enclosed chamber, means forsupporting a crystal therein, resilient means mounted externally of saidhousing and adapted to bring pressure to bear against said crystal toprevent movement thereof in said housing, said pressure means beingreleasable whereby to remove the pressure from the crystal.

JOSEPH G. BEARD.

